Over the last several years it has become apparent that the neurotransmitter serotonin (5-hydroxytryptamine-5-HT) is associated directly or indirectly with a number of physiological phenomena, including appetite, memory, thermoregulation, sleep, sexual behavior, anxiety, depression, blood pressure lowering and hallucinogenic behavior [Glennon, R. A., J. Med Chem., 30, 1 (1987)].
It has been recognized that there are multiple types of 5HT receptors. These receptors have been classified as 5-HT.sub.1, 5-HT.sub.2, and 5-HT.sub.3 receptors, with the former being further divided into the sub-classes 5-HT.sub.1A, 5-HT.sub.1B, 5-HT.sub.1C, and 5-HT.sub.1D. The binding affinity of a compound for one or more 5-HT receptors can provide a desirable physiological effect or minimize an undesirable effect. Therefore it is desirable to provide compounds which can bind to 5-HT receptors to act as serotonin agonists or antagonists.
Flaugh in U.S. Pat. No. 4,576,959 (issued 1986) and in European Patent Application 0153083 (published 1985) disclosed a family of 6-substituted-4-dialkylamino-1,3,4,5-tetrahydrobenz[cd]indoles which are described as central serotonin agonists. Leander in U.S. Pat. No. 4,745,126 (1988) disclosed a method for treating anxiety in humans employing a 4-substituted-1,3,4,5-tetrahydrobenz[cd]indole-6-carboxamide derivative.
It has now been found that certain 6- substituted-and particularly the 6-acyl substituted-4- aminotetrahydrobenz[cd]indoles are useful in treating conditions which can be benefited by a modification of 5-HT.sub.1 A receptor function in the body. It has been further found that certain of the instant compounds have substantial affinity for the 5-HT.sub.1D receptor and can be useful in treating conditions which can be benefitted by modifying 5-HT.sub.1A or 5HT.sub.1A and 5-HT.sub.1D receptor function in the body.